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Ventilation CFM required
Outdoor ventilation CFM for an occupancy per ASHRAE 62.1. Combines per-person rate (Rp) and per-area rate (Ra) by occupancy type. Result is the breathing-zone outdoor air; system intake will be higher after applying ventilation efficiency.
Breathing-zone outdoor air
290 CFM
People: 200 CFM (5 CFM/person × 40).
Area: 90 CFM (0.06 CFM/sf × 1500 sf).
Area: 90 CFM (0.06 CFM/sf × 1500 sf).
Per ASHRAE 62.1 breathing-zone outdoor air (Vbz = Rp×Pz + Ra×Az). Outdoor air at the air-handling unit (Vou) is higher after applying ventilation effectiveness (Ez = 0.8 ceiling supply / 1.0 floor supply / etc.) and zone multiple. Final design from the MEP engineer.
ASHRAE 62.1 reference rates
- Office: 5 CFM/person + 0.06 CFM/sq-ft
- Classroom: 10 CFM/person + 0.12 CFM/sq-ft
- Conference: 5 CFM/person + 0.06 CFM/sq-ft
- Retail: 7.5 CFM/person + 0.12 CFM/sq-ft
- Restaurant (dining): 7.5 CFM/person + 0.18 CFM/sq-ft
- Healthcare exam: 10 CFM/person + 0.18 CFM/sq-ft
Built by Forward
Forward runs ventilation CFM, duct sizing, HVAC load, CFM-for-BTU, and the broader NEC/IBC/IMC/IPC catalog over text.